A conventional X-ray tube emits a cone-shaped beam far wider than necessary to expose a limited area of a patient. It is therefore usual to control the cross sectional area of the beam radiated through the patient position by use of an X-ray attenuating mask or controller. Such controllers are sometimes called collimators although they do not collimate a beam into parallel rays. Masks of lead will substantially attenuate all X-radiation except through an X-ray transmissive window located on the central axis of the X-ray beam; a mask of aluminum will only partially attenutate the intensity of an X-ray, but is useful in subduing overly bright areas of an X-ray image. The more usual lead masks controllers are necessarily heavy and difficult to incorporate into a simple mechanism, accurately and repeatably adjusting the cross sectional size and shape of the transmitted beam. Prior controller mechanism are also bulky obstructing operations around the patient.
It is the object of the present invention to provide a simplified X-ray controller mechanism, with a minimal weight, which can define X-ray openings of variable shapes, sizes and orientation of a shaped opening with regard to the patient.